A variety of devices and methods for forming metal containers of aluminum and other metals have evolved over the years due to the continuous need for higher speed, metal use reduction and improved product appearance needs. In recent years there has been an increased emphasis on the provision of aluminum beverage containers having contoured xe2x80x9cshapedxe2x80x9d non-cylindrical sidewalls employing flutes, ribs, diamond, waffle or other patterns heretofore not obtainable with then known procedures. A substantial variety of approaches to the forming and shaping of metal containers and the like have evolved; however such prior art has not resulted in any high speed commercially satisfactory or acceptable devices capable of making metal beverage or the like containers with contoured sidewalls of the foregoing type.
Tominaga et al. U.S. Pat. No. 3,858,422 discloses a jet molding device using the impinging impact force of a waterjet deflected by a member 21 against the workpiece 9 to configure the workpiece to the contour of the cavity 11 of mold 12 in which the workpiece is positioned.
Inoue U.S. Pat. No. 3,566,647 discloses a system for deforming a workpiece 10 by the action of a high pressure jet projected from an amiable barrel 11A. A Pump 15B creates kinetic energy which is increased by an electrode 12 from which a spark discharge flows to the wall of tube 11 to provide a shock wave. The action of the shock wave and pressure jet supposedly provide a synergistic effect giving more energy than one would anticipate from the sum of the two items.
Burney U.S. Pat. No. 3,485,073 discloses an internal peening apparatus having a lance element 11 moved up and down and rotated while ejecting shot against the internal surface of a workpiece to harden the surface.
Koether U.S. Pat. Nos. 2,041,355 and 2,032,020 disclose outwardly expanding a piston wall by bombarding solid peening material forcibly thrown against the interior surface of the piston wall. The peening material is withdrawn through the conduits 31 and 32 and the pipe 25 may be moved longitudinally and rotated about its axis.
Johnson U.S. Pat. No. 4,353,371 discloses a method of pre-stressing the working surfaces of cylinders by shot peening followed by autofrettaging. The shot peening is effected by a rotating and reciprocating wand.
Faulkener et al. U.K. Patent Application Publication G.B. 2,224,965 a can reshaping apparatus employing compressed air fed through openings 56 in a mandrel 52 so that air pressure causes the can to expand to conform to the interior surface of a mold which can be opened and closed as shown.
Shimakata et al. (U.S. Pat. No. 4,265,102) discloses a method and apparatus for molding a container-like workpiece by the use of water pressure in a workpiece positioned internally of a separable upper mold half 30 and a lower mold half 19.
Coe (U.S. Pat. No. 5,524,466) discloses the use of hydraulic water jets provided through openings 8a in a hollow non-rotating xe2x80x9cneedlexe2x80x9d 5 for deforming a workpiece outwardly for shaping by die means 10,11 which can be opened and closed.
The present invention is in the field of apparatus and methods for forming aluminum or other metal beverage containers having contoured side walls and is specifically directed to the field of apparatus and methods employing high velocity liquidjets providing impact force, with minimal reliance on static pressure, for forcing the container wall into conformity with the inner wall of a mold to permanently deform and shape the container wall.
The invention uses the impact of high velocity fluid jets impacting the interior wall of a workpiece to force the wall outwardly into conformity with the contour of a surrounding mold in which the workpiece is positioned. More specifically, nozzles providing fluid jets are axially spaced on a rotary wand positioned internally of a can positioned upside-down in a surrounding mold. The mold is formed of two hinged components which are opened to initially received the workpiece and for removal of the finished can. The wand and jets are concurrently axially moved up and down and the wand rotated about its axis inside the workpiece so that the impact of the workfluid from the jets distorts the workpiece wall outwardly to conform with the internal surface of the closed mold. The workpiece is first prestressed with air pressure on its interior and the forced outwardly by the fluid jets to conform in the interior surface of the mold. A significant aspect of the invention is the fact that the spent working fluid is continually purged from the container by the air pressure in the workpiece by a drain line while the jets are simultaneously operating; thus, static pressure does not build up in the can. Multiple identical workstations each employing the foregoing structures are mounted for rotation on radial tables supported for rotation on a vertical support column to provide a continuous process in which workpieces are fed into the apparatus and finished containers are removed from the apparatus by infeed and outfeed vacuum starwheels to effect a high speed continuous operation.